The present invention relates generally to the monitoring of foam and gas carry under and controlling the use of defoaming chemicals in hydrocarbon systems. Still more specifically, the present invention relates to the monitoring of foam in high pressure separators and controlling the addition of defoaming chemicals in high pressure separators.
Crude oil is typically produced with large volumes of gas and/or water suspended in the crude oil. Because mixtures of oil, gas and water have the tendency to separate into distinct phases, it is often advantageous to separate the oil, gas and water at the production cite before shipment to downstream processing sites. However, problems have evolved in the design and development of such production site separation equipment. Specifically, the separation of the oil, gas and water into separate phases often may not occur due to system turbulence or short resonance times of the fluids through existing process equipment.
A standard piece of equipment for separating oil, gas and water at the production site is a separator. Separators are typically large vessels that allow the fluids sufficient resonance time to separate into the different phases. However, one problem associated with such separators is foaming. The foam is generated by gas that has been entrained in the crude oil as well as gas that has dissolved in the crude oil. Often, foam can be created by pressure drops that occur as the crude oil enters the separator. As a result, liquified and dissolved gases are released causing a layer of foam to be formed on the crude oil surface.
The presence of the layer of foam on the crude oil surface or gas carry under below the surface creates significant operational problems. Specifically, oil will be lost as the gas and foam is removed from the separator. In addition to the loss of oil, the presence of oil in the gas stream will cause problems in measuring the amount of gas produced. Further, downstream gas compressor operations can also be adversely affected by the presence of liquid/foam in the gas. Specifically, vessels designed to handle primarily gas can become flooded with foam and/or liquid.
On the other hand, if foam is transported downstream with the crude oil, the presence of the gas with the oil will result in unexpected and unmanageable amounts of gas being released in downstream processing equipment. Unfortunately, the above-described foam-related problems are not recognized until the process has already been compromised.
As a result, there is a need for a method of determining if foaming or gas carry under is occurring in separators, such as high pressure separators, and other processing equipment. Such methods and equipment would enable the operator to quickly determine if a foaming or gas carry under problem exists and further allow the operator to adjust the amount of defoaming chemicals being added to the system accordingly. Such a system would enable the operator to reduce the amount of defoaming chemicals being added to the system when the foaming and/or gas carry under is under control or not present thereby improving the efficiency of the system.